The present disclosure relates generally to semiconductor wafer fabrication, and more particularly to a method and apparatus for detecting backside contamination during fabrication of a semiconductor wafer.
Semiconductor integrated circuits are typically fabricated by a layering process in which several layers of material are fabricated on a surface of a wafer. Contamination on the backside of the wafer (i.e., the side of the wafer opposite to the surface being layered) is a significant contributor to problems during fabrication. In particular, contamination on the backside of the wafer may cause fabrication defects at a number of different processing steps. For example, the presence of backside contamination may cause over etching or under etching during the chemical etching process or during the chemical-mechanical polishing process (CMP). Moreover, the presence of backside contamination may also cause imaging-related defects during process steps such as photolithography, wafer inspection, or during rapid thermal annealing (RTA). Backside contamination may also be the cause of poor surface contact with the backside of the wafer during processes which utilize RF or heat transfer to the backside of the wafer such as during the etching process or RTA.
Large contamination particles may even be undesirably transferred to the front side of the wafer thereby potentially causing scratching of the front side of the wafer or the xe2x80x9cmicromaskingxe2x80x9d of a portion of the front side of the wafer. In some extreme case, the presence of backside contamination may even cause wafers to be broken due to stress or loss of vacuum pressure during wafer handling.
In accordance with one aspect of the present disclosure, there is provided a method of fabricating a semiconductor wafer. The method includes the steps of positioning the wafer in a wafer handling device, and detecting presence of a contaminant on a backside of the wafer while the wafer is positioned in the wafer handling device.
In accordance with another aspect of the present disclosure, there is provided an apparatus for fabricating a semiconductor wafer. The apparatus includes a wafer handling device. A contaminant sensor is secured to the wafer handling device. The contaminant sensor is configured to detect presence of a contaminant on a backside of the wafer when the wafer is positioned in the wafer handling device.
In accordance with a further aspect of the present disclosure, there is provided a method of detecting contamination on a backside of a semiconductor wafer. The method includes the steps of positioning the backside of the wafer in contact with a detection surface of a contaminant sensor, and detecting deformation of the detection surface of the contaminant sensor.